You could try to look into inotifywait to set a watch on that file, and parse its contents with sed, awk or whatever each time it's modified.
A basic watch would be:
inotifywait --monitor --even modify --format %w foo | \
while read file
echo "do whatever with file named \"$file\""
Now each time that the file called "foo" in the current directory changes, the while loop will be run.